In the type of hydrocarbon drilling operation where a drilling tool is redirected laterally through the side of a wellbore, it is common to use a downhole device known as a “deflector” depending from the lower end of the workstring or production tubing to “deflect” case-milling and drilling tools laterally. Where more than one lateral borehole is to be drilled from the wellbore, it is also common to reorient the deflector device by manipulating the workstring or production tubing (hereafter generally “tubing” or “production tubing”) from the surface, for example by rotating and/or lifting the tubing up and down to operate an indexing device that rotates the deflector. These methods require expensive, slow, and/or difficult-to-move machinery on the surface to lift the entire production tubing.
One such indexing deflector device is shown and described in our U.S. Pat. No. 7,669,672 which is incorporated in its entirety by reference.
FIG. 1 schematically shows such a prior art indexing deflector assembly, which generally includes a retractable tubing anchor 22, a deflector shoe 20, an indexer tool 18, and a tube segment or connector or landing profile 17 for connecting the deflector shoe to the production tubing 14. Milling and drilling tools, for example a jetting nozzle 16a, are lowered into operative engagement with the deflector shoe 20 via coiled tubing 16. Tubing 14 may also be connected directly to deflector shoe 20.
Details of such deflector assemblies are known to those skilled in the art and are not necessary for an understanding of the present invention. However, for context, the tubing anchor 22 is a device that contains slip devices that are outwardly biased to contact and “dig” into the sidewalls of the wellbore casing 12. The tubing anchor 22 is operated either mechanically by rotation of the production tubing 14 from the surface, or hydraulically by fluid pressure. The deflector shoe 20 is a tubular piece with a curving channel or passage 20a milled through it from its upper end, the channel entering the upper end of the deflector shoe 20 with an orientation parallel to its long axis and exiting a side of the deflector shoe perpendicular to the long axis. The shoe 20 is connected at its lower end to indexer 18 and the tubing anchor 22 and at its upper end to the production tubing 14. The indexing tool 18 is connected to the deflector shoe 20 to reorient the deflector shoe 20 in the wellbore 10 in response to a combination of up-and-down reciprocation and rotation of the production tubing 14, and thus change the radial direction in which casing-milling and borehole-drilling devices such as 16a are redirected through the deflector shoe 20 to engage the wellbore casing 12 and the surrounding formation 11.
In the illustrated example, the indexing tool 18 consists of two main tubular components, with the main portion of the first tubular component having an outer diameter slightly less than the inside diameter of the main portion of the second tubular component. A pin located on the outside housing of the second tubular component travels within a J-slot opening machined into the outside wall of the first tubular component. This J-slot has several profiles that are repeated to create an “endless J” path. At the end of each profile is a landing in which the pin lands to cause the first tubular component to be locked with respect to the second tubular component. The production tubing 14 must be lifted while it is rotated to allow the first tubular component to shift position with respect to the second tubular component, and in turn rotate the deflector shoe 20.